Combination alkylation and dehydrogenation process



Q QmSE R m J. A. CHENICEK Filed Oct. 30, 1956 Jan. 24, 1961 COMBINATION ALKYLATION AND DEHYDROGENATION PROCE suqmm m A. WW

m fi SE Y m tu umt United States Patent COMBINATION ALKYLATION- AND DEHYDRO- GENATIONPRQCESS l .[oseph A. Chenicek, Prairie view lll assjgnor, by. mesne, assignments, to Universal Oil, Proflucts Company, Des

hi is av conti u t mpart of, cont nding. appli ation 221. o- 44010.51, l d Jul a 29 1 5, and s1; h ch 11 turn, co t nua ionmpart of pplica ion r a fi ed Decetnber 2 1949,; an 1 9 abandoned. I l

' e present pp i late o a ovelr om in tion process including the reductive alliylationofan aromatic amino and/or. nitro compound with a ketone, during which step an alcohol is inherently formed from the ketone, and conversion ofthe alcohol'to a k etone f or furherit in the P FQ g ex a a be n. fou d that the alcohol'fraction as recovered ii the process must be treated in a specific manner in order to obtain satisfactory conversion thereof,- By thenovel combinationof reductive alkylation, special treatment of-the alcohol fraction, dehydrogenation of the alcohol to a ketone, and recycling of the ketone for further use in the process, an improved interdependent and mutually related process is evolved which produces increased yields of the desired products.

The novel process of the present invention is particularly-applicable to the production of N,N-di-sec-alkyl-pphenylene diamines, While these compounds may be utilized for any desired purpose, they are particularly satisfactory for use as antioxidants to prevent oxidative deterioration of organic compounds and particularly of motor fuel such as cracked gasoline, polymer gasoline, straight run gasoline, natural gasoline, etc., and mixtures thereof. Antioxidants for use in motor fuel include N,N'-di-isopropyl-p-phenylene diamine, N,N'-di-sec-butyl p-phenylene diamine, N,N-di-sec-amyl-p-phenylene diamine, N,N'-di-sec-hexyl-p-phenylene diamine, etc. A very satisfactory commercial antioxidant comprises N,N'-di-sec-butyl-p-phenylene diamine which may be utilized in cracked. gasoline in an amount of from about 0.0QQ 1% to about 0.1% and generally in an amount of from about 0.001% to about 0.01% by weight of the gasoline although lower or higher concentrations may be employed, when desired.

When used in organic compounds of higher molecular weight than gasoline as, for example, kerosene, diesel fuel, gas oil, mineral oil, lubricating oil, drying oil, fatty ma.- terials, rubber, plastic, resins, Waxes, adhesives, etc., N,N-di-sec-alkyl-p-phenylene diamines in which each alkyl group contains from 6 to 20 or more carbon atoms, more particularly from 8 to 12 carbon atoms, are generally preferred including, for example, N,N'-di-sec,- hexy -p-p y n d mi ,N'-di-s c-hepty -p-pheny ene diamine, N ,N-di-sec-octyl-pphenylene; diamine, N,N di secnonyl p-phenylene diamine, N,N"-di-secdecylrprphenylene diamine, N, N-di-sec-undecyhpphenylene diamine, -N,Nf*di-sec-dodecyl-p-phenylene diamine, N,N?-di-sec-tridecyl-p-phenylene diamine, N,N"-di-sec tetradecyl'vpfphenylene diamine, N,N -di-sec-,pentadecyl p-phenylene diamine, N,N"-di-sec-hexadecyl-prphenylenediamine, N,N di sec heptadecyl-pphenyleneL diamine, MN?di-sec octadecyhp-pl1enylene diamine, N,N -di-secice m dment h resen inven i n relat v to. a

omb atio pr es ic c rise dust ye al ylak ns a smnm nd. sel cted om h group ns in Qt romatic am nac mpo i r ma ni o ommands andarornatic aminocompounds with, a ketone, d n Whigh M 1.1. 1 11 r n l o me p a ing h flusnt Pro 2& ti he-re u e alk a i nta i 0'1,fta ti a satam aat d, w th an ami o. co d; ract o to separate. c h om a. .9 r .t st r hus eaatat a s ho o. a e. a, an upnly as sautls qa he q esal; meas re, alk at sn.

.11. a sr i embodiment h pre e n n o Islets-. 9, om na on pro ess. wh chc mpris sub ct ng a mp' uni.se stsqi r m. he staunconsisting 51 11 aniline. and'p-phenylene diamine to reductive alkylation with hydrogen and methyl ethyl ketone to form N,N'-diecr u yl-anhenylsas iamins nd? a e time o ing; a sec-butyl alcohol fraction contaminated with an amino compound, separating said, alcohol fraction from theother products of'the reductive alkylationand subjecting the same to fractionation to separate alcohol from amino compound, subjecting the thus separated alcohol to dehydrogenationto forrnmethyl ethyl ketone, and sup-, plying said ketone to the aforesaid reductive alkylatioii. In the reductive alkylation step ofthe process, an aromatic amino compound, aromatic nitro compound and/or aromatic aminonitro compound is subjected; to reductivealkylationwith-a ketone. Thetpreferred aromatic amino and/ or nitro compounds comprises p-phenylene diamine; and/or p-nitroaniline. Otheraromatic amino and/or nitro compounds include aniline, o-phenylene diamine, m-phenylene diamine, nitrobenzene, o-di-nitrobenzene, m-di-nit'robenzene, p di-nitrobenzene, o-nitr-oaniline, m-nitroaniline, 2,3-di-aminonitrobenzene, 2,4-di aminonitrobenzene, 2,6- di-arninonitrobenzene, 3,4 d-i aminonitrobenzene, 3,S-di-aminonitrobenzene, o-nitro-pa phenylenediamine, 2,3-di-nitroa-niline, 2,4-di-nitroanilirie', 2',5-di-nitroaniline,- 2,6-di-nitroaniline, 3,4-.di=nitroaniline, 3=,j5 -di-nitroaniline,' alpha-nitronaphthalene, beta-nitro: naphthalene, alpha-aminonaphthalene, beta-aminonaphthalene, and: otherbenzene, naphthalene, a-nthracene andphenanthrene derivatives. containing one or more. amino and/or nitro substituents. It is understood that. these aromatic amino and/or nitro. compounds may contain other substituents such as alkyl, aryl, alkaryl, aralkyl; cycloalkyl, allcoxy, hydroxy, sulfonic acid, halogen or other. substituents, but: not necessarily with. equivalent results.

In. the manufacture of N,N;':-di-sec:butyl-.pphmYlene diamine, the ketone for use in the reductive alkylation step com-prisesmethyl ethyl ketone. Examples, of; other ketones for: use in the manufacture of different com; pounds include dimethyl ketone, methyl propyl. ketone, methyl butyl ketone, methyl amyl ketone, methyl; hexyl ketone, methyl heptyl. ketone, methyl octyl ketone, methyl nonyl ketone, methyl" decyl ketone, methyl; un decyl ketone, methyl: dodecyl ketone, methyl tridecyl ketone, methyl tetradecyl ketone, methyl pentadecyl ketone, methyl hexadecyl ketone, methyl heptadecyl ke; tone, methyl octadecyl ketone, methyl nonadecyl ketone, methyl eicosyl ketone, etc., di-ethylketone, ethyl propyl ketone, ethyl butyl ketone, ethyl amylketone, ethyl hexylr ketone, ethyl. heptyl ketone, ethyl octyl, ketone, ethyl nonyl' ketone, ethyl decyl; ketone, ethyl undecyl ketone, ethyl dodecyl ketone, ethyl tridecyl ketone, ethyl tetradecyl ketone, ethyl pentadecyl: ketone, ethyl hexadecyl, ketone, ethyl heptadecyl ketone, ethyl; octa; decyli ketone, ethyl. nonadecyl: ketone, ethyl. eicosyl;1 ke; tone, .etc.,' diepropyl. ketone, propyl. :but-yl ketone, propyl amyl ketone, propyl hexyl ketone, propyl heptyl ketone, propyl octyl ketone, propyl nonyl ketone, propyl decyl ketone, propyl undecyl ketone, propyl dodecyl ketone, propyl tridecyl ketone, propyl tetradecyl ketone, propyl pentadecyl ketone, propyl hexadecyl ketone, propyl heptadecyl ketone, propyl octadecyl ketone, propyl nonadecyl ketone, propyl eicosyl ketone, etc., di-butyl ketone, butyl amyl ketone, butyl hexyl ketone, butyl heptyl ketone, butyl octyl ketone, butyl nonyl ketone, butyl decyl ketone, butyl undecyl ketone, butyl dodecyl ketone, butyl tridecyl ketone, butyl tetradecyl ketone, butyl pentadecyl ketone, butyl hexadecyl ketone, butyl heptadecyl ketone, butyl octadecyl ketone, butyl nonadecyl ketone, butyl eicosyl ketone, etc., di-hexyl ketone, hexyl heptyl ketone, hexyl octyl ketone, hexyl nonyl ketone, hexyl decyl ketone, hexyl undecyl ketone, hexyl dodecyl ketone, hexyl tridecyl ketone, hexyl tetradecyl ketone, hexyl pentadecyl ketone, hexyl hexadecyl ketone, hexyl heptadecyl ketone, hexyl octadecyl ketone, hexyl nonadecyl ketone, hexyl eicosyl ketone, etc., di-heptyl ketone, heptyl octyl ketone, heptyl nonyl ketone, heptyl decyl ketone, heptyl undecyl ketone, heptyl dodecyl ketone, heptyl tridecyl ketone, heptyl tetradecyl ketone, heptyl pentadecyl ketone, heptyl hexadecyl ketone, heptyl heptadecyl ketone, heptyl octadecyl ketone, heptyl nonadecyl ketone, heptyl eicosyl ketone, etc., di-octyl ketone, octyl nonyl ketone, octyl decyl ketone, octyl undecyl ketone, octyl dodecyl ketone, octyl tridecyl ketone, octyl tetradecyl ketone, octyl pentadecyl ketone, octyl hexadecyl ketone, octyl heptadecyl ketone, octyl octadecyl ketone, octyl nonadecyl ketone, octyl eicosyl ketone, etc. While the alkyl ketones generally are preferred, it is understood that ketones containing one or more aryl, alkaryl, aralkyl and/or cycloalkyl radicals may be employed but not necessarily with equivalent results.

The reductive alkylation of the aromatic amino and/or nitro compound with the ketone may be effected in any suitable manner. A particularly preferred catalyst for effecting the reductive alkylation reaction comprises an intimate mixture of copper oxide, chromium oxide and barium oxide. Other suitable catalysts include nickel, nickel-kieselguhr composites, nickel sulfide, copper sulfide, molybdenum sulfide, and those containing platinum, palladium, etc. The temperature to be employed generally will depend upon the particular catalyst to be utilized. When employing the mixture of copper oxide, chromium oxide and barium oxide catalyst, the temperature utilized is within the range of from 100 to about 250 C. The hydrogen pressure employed is within the range of from about to 200 atmospheres or more of hydrogen and preferably within the range of from about 35 to about 120 atmospheres. The mol ratio of ketone to aromatic amino and/or nitrogen compound is within the range of from about 2:1 to 20:1 or more and preferably is within the range of from about 2:1 to about 10:1.

The products from the reductive alkylation zone will comprise hydrogen, N,N-di-sec-alkyl-p-phenylene diamine, water, unreacted ketone, and sec-alcohol formed during the reaction along with amino compounds. The N,N' di-sec-alkyl-p-phenylene diamine is separated from the other products and is recovered as the desired product of the process. The unreacted ketone is separated from water and alcohol, and the ketone preferably is recycled to the reductive alkylation step of the process. The alcohol fraction is separated from the other products of the process and, in accordance with the present invention, is given a special treatment in order to obtain satisfactory dehydrogenation of the alcohol to the ketone for recycling of the latter within the process.

It has been found that the alcohol fraction as recovered in the process is contaminated with an amino compound or-compounds. The exact amino compound will depend upon the particular ketone used in the reductive alkylation step of the process. For example, in the reductive alkylation of p-nitroaniline with methyl ethyl ketone, it is believed that the sec-outyl-alcohol formed in the process is recovered as a fraction contaminated with secbutyl-amine and probably di-sec-butyl-amine, although it may comprise cyclohexyl amine or other amino compounds including entrained monoand/or polyalkylated aromatic amines. Regardless of the amino compounds contained in the alcohol fraction, it is an essential feature of the present invention that the alcohol fraction is subjected to fractionation or other treatment in order to remove the amino compounds prior to subjecting the alcohol fraction to dehydrogenation. As will be shown in the examples appended to the present specifications, a sec-butyl alcohol fraction as recovered from the products of reductive alkylation, when subjected to dehydrogenation in the presence of a brass catalyst, resulted in very poor yields of the desired ketone. However, upon fractionation of the alcohol fraction to remove amino compounds, the resultant alcohol fraction was dehydrogenated in the presence of the brass catalyst with good yields and long catalyst life. It will be noted that the necessity for such purification results from contamination occurring during the reductive alkylation step of the process and that the purification step results in the'production of high yields of ketones which, in turn, are recycled to the reductive alkylation step of the process, thus resulting in a series of interdependent and mutually related steps, thereby providing an improved unitary process for the production of N,N-di-sec-alkylp-phenylene diamines.

As hereinbefore set forth, the alcohol fraction as recovered from the effluent products of the reductive alkylation step of the process is subjected to treatment for the removal of amino compounds. In most cases, removal of amino compounds is readily accomplished by fractionation and, therefore, is a preferred method of treating the alcohol fraction. For example, in the reductive alkylation of p-nitroaniline and/or p-phenylene diamine with methyl ethyl ketone, the alcohol inherently formed in the reaction comprises sec-butyl alcohol. This alcohol has a boiling point of 995 C. and, therefore, is readily separated by fractionation from di-sec-butylamine (boiling point of 132 C.) or cyclohexyl amine (boiling point of 134 C.) or other amines which may inherently be formed in this step of the process. While fractionation is the preferred method of treating the alcohol fraction, it is understood that any other suitable method may be employed. The other method will depend upon the particular alcohol and amines and may comprise, for example, solvent extraction, use of a solid adsorbent to preferentially adsorb one or more of the components of the mixture, azeotropic distillation, etc.

The thus purified alcohol fraction is now subjected to dehydrogenation under conditions to form the corresponding ketone and hydrogen. As hereinbefore set forth, the alcohol will comprise a sec-alcohol including, merely for illustrative purposw, isopropyl alcohol, secbutyl alcohol, sec-amyl alcohol, sec-hexyl alcohol, secheptyl alcohol, sec-octyl alcohol, etc. While any suit able catalyst may be used for dehydrogenation, a preferred catalyst comprises brass consisting essentially of copper, zinc and lead. This catalyst preferably contains from about 56 to about 67% by weight of copper, from about 32 to about 42% by weight of zinc and from about 0.25 to about 3.5% of lead. When desired, the brass catalyst may be etched in any suitable manner, including etching with ammoniacal hydrogen peroxide, nitric acid or otherwise. Furthermore, it is understood that the catalyst may be used as turnings, cylinders, scrap or it may be formed into particles of uniform or irregular size and shape in any suitable manner. Other suitable catalysts include zinc oxide, copper and particularly copper oxide, etc. The temperature of dehydrogenation will vary with the particular catalyst employed but generally will be within the range of from about-2 50: to about 600 C. The pressure-employed rnay vary from about; atmosphericto -l-000 pounds or more but generally-is within the range of from about atmospheric to about 100 pounds per square inch.

The products from the dehydrogenation reaction will comprise a ketone, hydrogen and unreacted secondary alcohol; The secondary, alcohol is separatedand may be recycled for further processing, while the ketone and hydrogen are subjected to reductive alkylation with p-phenylene diamine or p-nitroaniline.

The novelty and utility of the present invention is further described in connection with the accompanying flow diagrammatic drawing which illustrates one specific embodiment of the invention but without the invention of unduly limiting the same thereto.

In the interest of simplicity, the drawing will be described with relation to the reductive alkylation of p-nitroaniline with methyl ethyl ketone. However, it is understood that the process flow, with suitable modification, may bejused for the reductive alkylation of other aromatic amino and/or, nitro compounds with methyl ethyl or other ketones. i

Referring to the drawing, p-nitroaniline and methyl ethyl ketone are introduced, to the process through line 1 andrare directed into reductive alkylation zone 2 Hydrogen is introduced through line 3' and is directed by Way of lines 4 and 1 to the reductive alkylation zone. The effluent products from zonev2 are directed through lineS to separation zone 6. In the case here illustrated, hydrogen is withdrawn through line 7 and, while all or a portion may be withdrawn from the process, at least a portion thereof is recycled by way of lines 4 and 1 to reductive alkylation zone 2 for further use therein. N,N'-di-sec-butyl-p-phenylene diamine is withdrawn from zone 6 through line 8 and is recovered as the desired product of the process. In the event. that this product contains some. mono-alkylated material, such as 'N-secbutyl-p-phenylene diamine, it is within the scope of the present invention to separate the mono-alkylated ma,- terial by any suitable method, not illustrated, and to re cycle the same to reductive alkylation zone 21 for further conversion therein. The remaining efliuent prod.- ucts fromthereductive alkylation zone are supplied from separation zone 6 by way of line 9 to separation zone 10.

The efiluent products introduced. into separation zone 10 are treatedv to separate water, unreacted ketone and an alcohol fraction, the latter being contaminated with amino compound or compounds. In the case here illustrated, water is removed from the. upper portion of zone 10 by way of line 11. This is accomplished by introducing a suitable material which forms an azeotrope with the water and thereby permits its removal as a lower boiling fraction. Any suitable =azeotropic material may be used and may comprise a hydrocarbon as, for example, cyclohexane. Line 19 is provided for introducing. the azeotropeforming. compound, although it may be supplied to. zone 10 in any suitable manner. The azeotrope. withdrawn. through, line 11 preferably is treated in any suitable manner, not illustrated, and the azeotrope forming. material is recycled for fulther use in the process. In the. event that. the azeotrope forming material is not utilized, the water may be removed from the other products in any suitable manner. Unreacted methyl ethyl ketone is Withdrawn from zone 1.0; through line 12 and, while'allor. a portion. may beremovedlfrom the process, preferably at least a portion thereof is recycled by way of lines 13 and 1 to reductive alkylation zone 2 for further use in the process.

The contaminated alcohol fraction is withdrawn from zone 10 by way of line 14 and, in accordance with the present invention, at least a portion thereof is directed by way of line 15 to zone 16 for separation of the alcohol from amino compound. In the case here illustrated, the purified alcohol is withdrawn from Zone 16 through line 17 and is directed through line 18 to depound or compounds are withdrawn from zone 1 6 through line 21 and may be discarded or utilized for any desired purpose. Line 22 is provided forthe separation and removal of any water-ketone azeotropeor other-low boiling material which'may be carried over into zone 16. In some cases, it is unnecessary to separately remove the'lower boiling material and, in such cases, the alcohol fraction substantially free from amino compounds may be withdrawn from the upper portion of zone 16 and supplied directlyto dehydrogenation zone 20 in any suitable manner, not illustrated. As hereinbefore set forth, it is essential that the alcohol fraction be substantially free from amino compound before being subjected to dehydrogenation.

The alcohol fraction is subjected to dehydrogenation in zone 20, and the effluent products are withdrawn through line 23 and are directed to separation zone 24. In zone 24 ketone and hydrogen are separated from unreacted alcohol. The unreacted alcohol is withdrawn through line 25 and, while all or a portion may be removed from the process, preferably at least a portion thereof isrecycled by waylof lines 2 6 and 18; to zone 20 for further conversion therein. The-ketoneand hydrogen separated in zone 24 are removed therefrom byway of line 27 and, in accordance with the invention, at least a portion thereof is recycled by way of lines28,- '13 and 1 to reductive alkylation zone 2 for further use within the process.

It is understood that thevar-ious separation zones illus; trated inthedrawingmay comprise one ormore of such zones and also that the separation may be effected in any suitable manner, including distillation, solvent: extraction, etc. When fractionation means, are employed, it is understood that the separation zones will be equipped with suitable heating, means in the lower. portion thereof and suitable cooling means in the upper portion thereof so that eflicient fractionation is obtained. Furthermore, in the interest of simplicity, valves, pumps, heaters and similar appurtenances have been omitted; from the drawing.

The following examples are introduced to illustrate further the noveltyv and utility. of the invention but: not with the intention ofunduly limiting thesame.

Example I Reductive alkylation of p-nitroaniline withmethyl. ethyl ketone is effected in the'prese'nce of a mixture of chromium oxide, copper oxide and barium oxide catalyst (molar portions-.10CR O :IOCuOzlBaO) at a temperature of C., a hydrogen pressure of 60 atmospheres, while utilizing 8' mols of methyl ethyl ketone per mol of p-nitroaniline. The products from the reductive alkyla} tron zones are fractionated to separate N,N'-di-sec.-butylp-phenylene diamine from hydrogen, unreacted ketone, water and sec-alcohol amino compounds. The hydrogen and ketone are recycled to the reductive alkylation step of the process, while the sec-alcohol-amino compound fraction is subjected to fractionation to separate sec'butyl alcohol from amino compound.

The thuspurified sec-butyl alcohol fraction is subjected to dehydrogenation at 420 C. in the presence of a catalyst consisting of 60%, by. weight of copper, 37% by weight of zinc and 3% by weight of lead, Methyl ethyl ketone and hydrogen are separated from unconvertedsecbutyl alcohol, the latter being recycled to the dehydrogenation step of the process, while the methyl ethyl ketone and hydrogen are supplied to the reductive alkylation step of the process.

Example 11 This example compares the results obtained in the dehydrogenation of (A) sec-butyl alcohol fraction as recovered from the reductive alkylation efiluent products and (B) the sec-butyl alcohol fraction after fractionation to remove approximately 3% of other materials (amino compounds). Fraction A comprised 16% methyl ethyl ketone, 81% sec-butyl alcohol and 3% other materials. Fraction B comprised 16% methyl ethyl ketone and 84% sec-butyl alcohol.

Fraction A was subjected to dehydrogenation in the presence of a brass catalyst at a temperature of about 565 C. The products of the dehydrogenation contained only 17% methyl ethyl ketone and 81% unconverted sec-butyl alcohol. This amounts to a percent conversion of alcohol to ketone of only 1.2.

Fraction B was separately subjected to dehydrogenation in the presence of the same catalyst at a temperature of about 460 C. In a once-through operation, the product consisted of 50% methyl ethyl ketone and 50% alcohol, thus amounting to a percent conversion of alcohol to ketone of 40.5.

It will be noted that the purified sec-buty1 alcohol fraction resulted in considerably higher conversion to methyl ethyl ketone when the alcohol fraction was fractionated to remove amino compounds prior to the dehydrogenation.

Example III The runs reported in Example II were effected in a continuous type operation. In order to confirm that the improved results were due to the pretreatment of the alcohol fraction, the charge to the dehydrogenation was switched back to fraction A (alcohol fraction not treated to remove amino compounds). The products from dehydrogenation of fraction A contained only 17% methyl ethyl ketone and were substantially equivalent to the results obtained originally with this untreated alcohol fraction.

The data in these examples clearly show the improved results obtained by treating the alcohol fraction recovered from the reductive alkylation products in order to remove the high boiling amino compounds prior to dehydrw genation.

I claim as my invention:

1. A combination process which comprises reductively alkylating a compound selected from the group consisting of aromatic amino compounds, aromatic nitro compounds and aromatic aminonitro compounds with a ketone, during which an alcohol is inherently formed, separating from the eflfluent products of the reductive alkylation an alcohol fraction contaminated with an amino compound, treating said fraction to separate alcohol from amino compound, recovering an alcohol fraction substantially free from amino compound and dehydrogenating the thus separated alcohol to a ketone, and supplying said ketone to the aforesaid reductive alkylation.

2. A combination process which comprises reductively alkylating a compound selected from the group consisting of aromatic amino compounds, aromatic nitro compounds and aromatic aminonitro compounds with a ketone, during which an alcohol is inherently formed, separating from the effluent products of the reductive alkylation an alcohol fraction contaminated with an amino compound, subjecting said fraction to fractionation to separate an alcohol fraction from a higher boiling amino compound fraction, separately withdrawing from said fractionation an alcohol fraction substantially free from amino compound and subjecting the alcohol fraction to dehydrogenation to form a ketone, and supplying said ketone to the aforesaid reductive alkylation.

3. A combination process which comprises reductively alkylating p-nitroaniline with a ketone, during which an alcohol is inherently formed, separating from the efiluent products of the reductive alkylation an alcohol fraction contaminated with an amino compound, treating said fraction to separate alcohol from amino compound, recovering an alcohol fraction substantially free from amino compound, and dehydrogenating the thus separated alcohol to a ketone, and supplying said ketone to the aforesaid reductive alkylation.

4. A combination process which comprises reductively alkylating p-phenylene diamine with a ketone, during which an alcohol is inherently formed, separating from the effluent products of the reductive alkylation an alcohol fraction contaminated with an amino compound, treating said fraction to separate alcohol from amino compound, recovering therefrom an alcohol fraction substantially free from amino compound, dehydrogenating the thus separated alcohol to a ketone, and supplying said ketone to the aforesaid reductive alkylation.

5. A combination process which comprises subjecting p-nitroaniline to reductive alkylation with hydrogen and methyl ethyl ketone to form N,N'-di-sec-butyl-p-phenylene diamine and at the same time forming a sec-butyl alcohol fraction contaminated with an amino compound, separately recovering said alcohol fraction from the other products of the reductive alkylation, and subjecting the same to fractionation to separate alcohol from amino compound, recovering therefrom an alcohol fraction substantially free from amino compound, and subjecting the thus separated alcohol to dehydrogenation to form methyl ethyl ketone, and supplying said ketone to the aforesaid reductive alkylation.

6. The process of claim 5 further characterized in that said dehydrogenation is elfected in the presence of a brass catalyst.

7. A combination process which comprises subjecting p-phenylene diamine to reductive alkylation with hydrogen and methyl ethyl ketone to form N,N'-di-sec-butylp-phenylene diamine and at the same time forming a secbutyl alcohol fraction contaminated with an amino compound, separately recovering said alcohol fraction from the other products of the reductive alkylation, and subjecting the same to fractionation to separate alcohol from amino compound, recovering therefrom an alcohol fraction substantially free of amino compound, and subjecting the thus separated alcohol fraction to dehydrogenation to form methyl ethyl ketone, and supplying said ketone to the aforesaid reductive alkylation.

8. The process of claim 7 further characterized in that said dehydrogenation is effected in the presence of a brass catalyst.

References Cited in the file of this patent UNITED STATES PATENTS 1,460,876 Williams et al. July 3, 1923 1,952,702 Simo Mar. 27, 1934 2,028,267 Archibald et al. Jan. 21, 1936 2,083,877 Stock et a1 June 15, 1937 2,323,948 Von Bramer et al July 13, 1943 2,472,493 Schneider et al. June 7, 1949 2,498,630 Thompson Feb. 28, 1950 OTHER REFERENCES Young: Distillation Principles and Processes, p. 196

(1922), Macmillan and Co., London. 

1. A COMBINATION PROCESS WHICH COMPRISES REDUCTIVELY ALKYLATING A COMPOUND SELECTED FROM THE GROUP CONSISTING OF AROMATIC AMINO COMPOUNDS, AROMATIC NITRO COMPOUNDS AND AROMATIC AMINONITRO COMPOUNDS WITH A KETONE, DURING WHICH AN ALCOHOL IS INHERENTLY FORMED, SEPARATING FROM THE EFFLUENT PRODUCTS OF THE REDUCTIVE ALKYLATION AN ALCOHOL FRACTION CONTAMINATED WITH AN AMINO COMPOUND, TREATING SAID FRACTION TO SEPARATE ALCOHOL FROM AMINO COMPOUND, RECOVERING AN ALCOHOL FRACTION SUBSTANTIALLY FREE FROM AMINO COMPOUND AND DEHYDROGENATING THE THUS SEPARATED ALCOHOL TO A KETONE, AND SUPPLYING SAID KETONE TO THE AFORESAID REDUCTIVE ALKYLATION. 